1. Technical Field
The present invention relates generally to data processing systems, and in particular, to methods handling path flow exception and finalization processing in an object oriented programming language.
2. Description of Related Art
In languages like C or C++, most errors, such as accessing an array element beyond the end of an array, are undetected. Those errors that are detected, such as an attempt to divide a number by zero, usually cause the program to print out a brief error message and terminate immediately.
A Java system""s error handling is more sophisticated. When an error occurs in a method while a program is running, an exception is generated. The method then deals with the exception in one of two ways: with an exception handler or by throwing the exception. An exception handler is a section of the program that checks for a particular type of exception and then executes if the exception occurs. Throwing an exception refers the exception back to the method that called it. If an exception is thrown to the calling method, then this method can in turn either handle the exception in its own exception handler, or throw the exception to its caller. This process continues until either some section of the program handles the exception, or the exception gets thrown to the system. For example, the exception would be thrown to the system when the main method throws an exception. If the system is thrown an exception, it handles it by printing an error message and terminating the program that caused the exception.
An important part of understanding path flow is by instrumenting calls to individual routines. However, in object oriented programming languages such as Java, the flow of control can also include exception and finalization processing. Without including exception processing, during postprocessing exit events may be found that do not have matching entry events, thus the post processing results are subject to incorrect results.
It would be advantageous to provide instrumentation support for exceptions.
The present invention is directed to a system, method and instructions for handling path flow exception and finalization processing in an object oriented programming language. Initially, each instrumented method is checked for a code to indicate an exception being thrown. A hook is inserted before the exception code and identifies the method throwing the exception. Methods must also be checked for exception tables. When an exception table is found, then a hook is inserted at the entry point of each exception handler for every entry in the exception table. This hook identifies the method which catches the exception or handles finalization processing.